Pollen Analysis of the Cores obtained from the Bottom of Tokyo Bay

Abstract

The writer aimed at the zoning of Alluvial deposit of Tokyo Bay, from the view point of pollen analysis. Two boring cores were obtained, one was at the Warf of Harumi, Tokyo, and another, KI-10 at a locality 5km off Hunabashi City, Chiba Prefecture (Fig. 1). These two pollen spectra are shown in Figs. 2 and 3. The lists of rare specimens are shown in Tables 1 and 2. The cores are lithologically classified in ascending order as follows: Diluvial silt, basal sand, lower clay, middle sand and clay, upper clay, and upper sand. They roughly coincide with Zone W, MW, A, C, T and P of pollen respectively, and are Alluvial except Zone W (Table 3). The climate of Zone W is considered to be cool as proved by the occurrence of such pollens as Abies, Picea, Tsuga, Fagus and Patrinia. The last one is said by Shimakura (1961) to be one of the indicator of a cool climate of Japanese Quaternary (see the Plate). In Zone MW the flora is gradually changing towards the lowest zone. Zone A shows a warm climate and characterized by Alnus which may be a local phenomenon. Zone C comprises abundant coniferous trees, mostly Cryptomeria. Therefore the writer assumes that the climate changed from warm to cool. Zone T is characterized by broadleaved trees (Tricolporo-pollenites spp.) indicating a warm climate similar to that of today. Pollens of recent Pinus are abundant in Zone P.